Doweled base for adjustable directional lamp



Dec. 22, 1959 A. M. KRUPP 2,913,645

DOWELED BASE F'OR ADJUSTABLE DIRECTiONAL LAMP Filed Aug. 22, 1957 lnven tor: An hon M. Kvupp,

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United States Patent DOWELED BASE FOR ADJUSTABLE DIRECTIONAL LAMP Anton M. Krupp, Gates Mills, Ohio, assignor to General Electric Company, a corporation of New York Application August 22, 1957, Serial No. 679,631

2 Claims. (Cl. 339-2) The present invention relates to lamp bases and particularly to rotatable base constructions for linear doubleended lamps having a directional light output in a plane transverse to the longitudinal axis of the lamp envelope.

Rotatable bipin base constructions for a lamp of this type by which the lamp envelope is adjustable on its longitudinal axis to change the direction of maximum light output without changing the position of the base contact pins in lamp holders are disclosed and claimed in the copending application of Dale A. Grovemiller and Joe L. Elam, Serial No. 619,485, filed October 31, 1956, now Patent No. 2,864,067 dated December 9, 1958, and

the copending application of John W. Fulton and Robert A. Kuebler, Serial No. 619,486, filed October 31, 1956. Both of these applications are assigned to the assignee of the present application.

Both the copending applications disclose tubular fluorescent electric discharge lamps having a longitudinally extending light transmitting window along one side of its vitreous envelope, a pair of current inlead wires eX- tending from each end of the envelope and rotatable bipin bases mounted on the ends of the envelope and fastened to the inleads. Each of the bipin bases comprises a cylindrical shell having a rim portion attached antiturningly to an end of the lamp envelope and a contact pin assembly including a pair of mutually insulated contact pins and a pin supporting member. The contact assembly is mounted for rotation on the base shell with its axis of rotation coincident with the longitudinal axis of the shell which is coaxial with the lamp envelope. The

pins are symmetrically arranged with respect to the longitudinal axis and are in a diametral plane of the shell. The lamp envelope thus is rotatable on its longitudinal axis with respect to the diametral plane of the pins to orient the directional lamp in lamp holders without movingthe pins in the holders.

In order to avoid short circuiting the inlead wires, the

relative movement of the shell and the contact pin assembly is limited to an angular distance of approximately 110. The window extends an angular distance of 140 degrees around the circumference of the envelope. It has been found advantageous for obtaining a desired light distribution as described in the copending Fulton et al. application to so mount the bases in such position on the ends of envelope that, with the base shell and thepin support at their mid-pont of relative rotation,

the median plane of the window and the diametral plane of the pins are at an angle of approximately 40 degrees with respect to each other.

In order to so mount the bases on the ends of the envelope it is necessary to have the base shell and the pin assembly at their mid-point of relative rotation while attaching the bases to the envelope ends. The principal object of the present invention is to provide a rotatable base construction including integral means for positively locking the base shell and the pin support together at their mid-point of relative rotation so as to prevent their relative rotation before the base shell is afiixed to the envelope. Another object of the invention is to provide such positive locking means which is readily broken by hand after the base shell is aflixed to the lamp envelope to release the locked parts of the base for relative. rotation. Further objects and advantages of the invention will appear from the following description of a species thereof, the accompanying drawing and the appended claims.

The invention attains its objects by doweling the base shell and the contact pin assembly together by a frangible pin which is readily broken off by manual relative rotation of the shell and the assembly. In the preferred embodiment of the invention, the dowel pin is made integral with a contact pin support of thermosetting organic electrically insulating material and engages the sides of a hole in the shell to lock the shell and the support together against relative rotation. The pin is broken off from the support by a shearing action when the shell and the support are manually rotated relative'to each other after the shell has been affixed to the lamp envelope.

The invention will be readily understood from the following description and the accompanying drawing in which is shown the preferred embodiment of the inven tion.

In the drawing:

Fig. 1 is a pictorial view of a directional lamp equipped with bases embodying the invention.

Fig. 2 is an enlarged end view of one of the bases shown in Fig. l and as viewed from the envelope engaging end of the base.

Fig. 3 is a sectional view of the base shown in Fig. 2 taken along the line 3-3 of Fig. 2 and showing in section an end of the lamp envelope to which the base is cemented.

Fig. 4 is similar to Fig. 3 with the parts thereof rotated and the section of the base taken along the line 44 of Fig. 2.

Fig. 5 is an enlarged end-on view of the lamp shown in.Fig. l, and

Fig. 6 is a pictorial view on an enlarged scale of a lamp holder suitable for the lamp equipped with bases of the type illustrated in Figs. 1 to 5.

Referring to Fig. 1, there is shown an elongated tubular double-ended fluorescent lamp having a sealed vitreous light-transmitting envelope 1 provided with bipin bases 2 and 3 of identical structure attached to the ends thereof. The envelope 1 transmits light passing through a window 4 defined by an internal reflecting coating 5 provided on the upper portion of its circumference. The common boundaries of the window 4 and the coating 5 are indicated by the lines 6 and 7 in Figs. 1 and 5 of the drawing. The reflecting coating 5 is interposed between the inner surface of the envelope l and the usual phosphor coating 8 extends around the entire circumference of the envelope 1 so that light produced by phosphor coating 8 is directed by the reflecting coating 5 through the window 4. The lamp thus has a directional characteristic in that it emits more light in the direction in which the window faces than in any other direction. The coating 5 is preferably partially light transmitting.

In structural features other than the bases attached to the ends of the tubular envelope 1 the lamp illustrated is similar to commercial fluorescent lamps having a nondirectional characteristic in that it is provided with an ionizable atmosphere including an inert starting gas, such as argon, at a low pressure and a small quantity of mercury indicated by the droplet 9. The lamp is provided at the ends of the envelope 1 with filamentary electrodes 10, one of which is shown in Figs. 1, 3 and 5, including a :.3 tungsten support" and electronemissive oxide material on said support. The electrodes are of the hot starting type, that is, required either preheating current at starting or continuous heating eurrent during startingandoperation. Ap'air offlexible current tlead-ing in wires';11' and 12 are sealed into' thestems 13 at each end of I the lamp envelope 1 for-condueting preheat and-operating current to the electrodes 10.

During operations of t-he lamp, :1- low pressure mercury vapor dischargeHbetween the electrodes 2 within the -envelope 1 causes productionofi -resonanceradiation at each base comprises a' cylindrical=cup-shaped metal shell 14, suchas an aluminum shell,--adapted'-to:be cemented at its rim portion to the-reduced end portion of the envelope 1; as shown inFig. 3,- and a-pair of spaced parallel insulated contact pins and 16 projecting outward in a longitudinal direction -from the'ends Y of the. based lamp for engagement with lampholder contacts. The-pins 15 and 16 are symmetrically arranged with respect to and are in a diametral planeincluding-'thetlongitudinal axis ofthe lamp envelope 1 which: isusual. in fluorescent lamps when thebases are properly mounted on the envelope ends.

The bases 2 and 3 are of the type-disclosed and claimed in the copending Grovemiller et al. application referred to above and in which the contact pins 15 and 16 of each base are included in anxassembly including also a disk 17 of thermosetting organicplastic insulating material, such as Bakelite, pivoted at its center'to'the center of an integralcircular-web 19 on the shell 14. The ends of the pins 15 and 16 are molded into the disk 17. The pivot pin is in the form of a rivet :18 which permanently fastens the shell 14 and the disk 17 together and allows the disk and the shellto rotate .with respect to each other. The envelope; 1 of a lamp a mounted in lamp holders thus may be turned on its longitudinal' axis to change the position of'the window' 4 without changing the position of the contact pins 15 and 16in the lamp holders.

Twisting together, of the .wires. 11. and: 12 :is prevented by the arcuate slots 20 and 21;;in thecircular web 19 of the shell 14 and the annular protrusions 22 and 23 on the side of the disk 17 .engagingthe web 19. The protrusions extend into the slots and the slots and the protrusions are proportioned tolimit the relative rotation of the shell 14 and the disklto about 110 while allowing such rotation within theselirnits. The protrusions are hollow and the wires 11 and .12 extend therethrough and are attached tothepins 15. and 16 as shown in Fig. 3.

In mounting the base'on-the end of the envelope 1 it is advantageous 'to havethe base shell 14 and the contact pin assembly at their midpoint of rotation and the diametral plane: of the contact pins and the common plane of the electrodes 10- and the inlead wires at each end of envelope 1 coincident, as shown in Fig. 5, in which the line AB'indicates the position of these planes. The

envelope 1 of a-ubased lamp then may be rotated 55 from the mid-point of rotation in either direction without twistingthe wires 11 'and'12, together.

AS'dlSClOSGdlH thefiabove' referred to copending applications, it is advantageous .for' obtaining a desired light distribution to correlate the position of the median plane C-D of.the'window@4 .(Fig. 5) and the diametral plane AB of the pins 151andz 16., in, such manner that these planes are at an angle of approximately 40 with respect to each other when the shell 14 and the assembly including disk 17 are at. their'mid-point of rotation.

For convenience in mounting the. bases 2 and Son the envelope 1 with the diametral plane of the pins and the medianplaneof-the window properly correlated, thedisk 17 is provided with a pointer 24 at right angles to the diametral plane AB of the pins, and the shell 14 of each of the bases 2 and 3 is provided with two radially extending ribs 27 and 28 spaced an angular distance of 40 from each other and symmetrically arranged with respect to a plane EF normal to a diametral plane includingthe mid-points of the slots 20 and 21, such as the plane AB.

When the pointer'24 is positioned midway between the ribs27- and 28, the disk 17 and the shell 14 are at the mid-point of their relative rotation. With the pointer 24 so positioned on each base-the shell 14 of base.2 (Figs. 1 and 5) is cemented to the end of envelope 1 with the rib 27 in alignment with the boundary 6 of the window 4 and the rib 28 located between the boundaries 6 and 7. The base 3 (Figs. 1 to 4) of identical structure is cemented to the opposite end of theenvelope l' with the rib 28 in line with the boundary 6 and the rib27xbetween the boundaries 6 and 7.

With the bases-so mounted on the ends ofthe envelope 1 the latter is rotatable on its longitudinal axis an angular distance of 55 in either direction with respect to the common diametral plane of the pins 15 and 16011 the bases 2 and 3.

Thus, when-the based lamp is mounted between a pair of conventional lamp holders, such as holders of the type shown at 30in Fig.6, the envelope 1 may be rotated on its longitudinal axis to change the direction of maximum light output of the lamp without changing the position: in the holders of the base contact pins 15 and 16' which engage the slightly'V-shaped partsof the holdermetal. contacts 37 and 38.

The bases disclosed and claimed in the copending applications referredto above include a detent arrangement intended to hold the base shell 14 and the (11816.17 at their mid-point of rotation while mounting and cementing the bases to the ends of: the lamp envelope. The

detent is constituted by dent 25in the web 19 of the shell 14 and an arcuately arranged series of notches 26 in the web engaging face-of the disk 17. Inthe copending. ap-

plication of. Grovemiller et al. the .web; of thel-baseuis sprung slightly inward of the shell to hold the disk against the shell to supplement the holding forceofzthe detent. These. arrangements tend to hold these base parts against casual relative rotation both before:and after .the bases are mounted on the ends of .the envelope. However, the holding forceobviously must be less than .the torque required to. turn the pins in the holders of ,was not always effective for holding against relative rotation the base shell and the pin assembly while the bases were being transported in bulk and separately handled and manipulated incident to mounting and cementing .the bases, on the ends of the lamp envelope. This relative rotation would resultin bases being cemented to the envelope ends with the shells 14 and pin assemblies; offset from their mid-point of rotation so that, the: completed lamp would have to be rejected. This increased .the cost of manufacture of such lamps.

By doweling the shell, and the, disk together, in, accordance with the presentinvention and as shown in'Fig.':4, this difliculty is avoided in a positive and inexpensive manner. Referring to Fig. 4, the frangible dowel pin 39 is formed integral withthe .disk 17 and projects fromthe face ofthe disk engaging the web 19 of the shell 14. @A hole 40 for the dowel pin 39 is provided in the web 19 of the shell 14 and the pin 39 engages the sides of the hole to lock the shell 14 and the disk 17 together against relative rotation until the mounting of the base on the envelope end has been completed in the manufacture of the based lamp. After the shell has been aflixed antiturningly to the envelope end by the heat cured basing cement in the usual manner, the pin assembly including disk 17 may be rotated by hand relative to the base shell 14 to break off the frangible pin 39 from the disk 17 to unlock the disk and the shell for relative rotation subject to the holding force of the detent and the frictional engagement of the disk and the web of the shell, as mentioned above.

When the pin is made of phenolic resin, such as Bakelite, a pin diameter of 0.040 inch and length of 0.125 inch has been found satisfactory for use with a hole having a diameter of 0.062 inch and a depth of 0.010 inch.

While I have shown and described an illustrative embodiment and the best mode of carrying out the invention, it will be understood that I contemplate that changes in the form and details of the base may be made without departure from the spirit and scope of the invention as defined in the appended claims, for example, the dowel pin 39 and the hole 40 may be provided at other locations than diametrically opposite the pointer 24 and the pointer 24 may be omitted inasmuch as the shell 14 and the disk 17 are doweled together at their mid-point of relative rotation when these base parts are fastened together by the rivet 18 in assembling the base. I prefer to retain the pointer 24, however, because it is helpful in properly mounting a based lamp between its holders 30 by indicating the rotative position of the contact pins 15 and 16 with respect to the contacts 37 and 38 of the holders to show when the pins are in the V-shaped parts of the holder contacts.

What is claimed is:

1. A lamp base comprising a cylindrical shell having a rim portion for attachment anti-turningly to a lamp envelope and an integral circular web at the end thereof opposite said rim, a contact pin assembly comprising a pair of mutually insulated contact pins and a support holding said pins in spaced parallel positions, said support being pivoted for rotation on said web with its pivotal axis coincident with the longitudinal axis of said shell, said pins being symmetrically arranged with respect to the longitudinal axis and in a diametral plane of said shell, said shell and said pivoted support having inter-engaged parts including a frangible pin for mounting said base on the lamp envelope with said shell and said support locked in predetermined relative rotational positions and for releasing said shell and said support for relative rotation after such mounting.

2. A lamp base comprising a cylindrical metal shell having a rim portion for attachment anti-turningly to a lamp envelope and an integral circular web at the end thereof opposite said rim, a contact pin. assembly comprising a pair of mutually insulated contact pins and a support holding said pins in spaced parallel positions, said support consisting of a disk of insulating material pivoted for rotation on said web with a face thereof engaging said web and with its pivotal axis coincident with the longitudinal axis of said shell, said pins being symmetrically arranged with respect to and in a diametral plane of said shell, said web being perforated and said disk having an integral frangible dowel pin projecting from the face thereof engaging said web and into the perforation in said web to hold said shell and said disk against relative rotation during mounting of said base on a lamp envelope.

References Cited in the file of this: patent UNITED STATES PATENTS 1,817,004 Hubbell Aug. 4, 1931 2,235,656 Thal Mar. 18, 1941 2,386,190 Betts Oct. 9, 1945 the longitudinal axis 

